Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$ 6.8	$ 8.4	$ 26.4	$ 41.8
Operating cash flows for finance leases	0.1	0.3	0.5	1.2
Financing cash flows for finance leases	0.2	5.6	8.1	24.0
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	0.2	3.4	2.3	9.7
Finance leases	$ 0.5	$ 0.3	$ 1.5	$ 0.4